John Swinney is expected to be crowned Scotland’s next first minister within days after his only rival ruled herself out and promised to support his candidacy. Kate Forbes, the former finance secretary who came close to winning the Scottish National party leadership last year, said she was persuaded to step aside because Swinney had promised he would “govern from the mainstream”. Barring a surprise challenge, Swinney is likely to be confirmed as the SNP’s next leader without a contest on Monday afternoon and become first minister in the two days after that. Two activist party members who are adamant a contest is needed are said to be canvassing support from other activists. They have until Monday lunchtime to gather 100 signatures from 20 party branches in order to stand. Humza Yousaf dramatically quit on Monday after he unilaterally abandoned a three-year-old alliance with the Scottish Greens, causing the Greens to back a vote of no confidence tabled by the Scottish Conservatives. In a statement on Thursday morning announcing he would stand, Swinney presented himself as a unifier able to rescue his party from its current crisis and infighting. “I could have stood back and hoped others would sort things out. But I care too much about the future of Scotland and the Scottish National party to walk on by,” he said. “Just as we must fight against the polarisation of our politics, we cannot allow the SNP to be polarised.” Swinney, 60, also sought to kill off speculation that he was standing as a caretaker. He served as party leader between 2000 and 2004, quitting after repeated attacks from internal critics. “I’m not a caretaker. I’m not an interim leader,” he said. “I’m offering to lead my party through the Westminster elections, lead us beyond the 2026 elections – two contests I intend to win for the SNP.” Forbes’s decision saves the SNP from a rerun of the bruising contest between her and Yousaf, during which she accused him of repeated incompetence and she came under attack for her conservative Christian stance on same-sex marriage, abortion and gender recognition. Swinney has to reunite a divided party after the crisis caused by the implosion of the alliance with the Greens, while walking a tightrope as the leader of a government two votes short of an overall majority. That will require reintegrating Forbes’s allies in the party, many of whom are socially conservative, without alienating the Greens, whose seven votes could be crucial. On the climate emergency, Swinney signalled his government could slow down or drop some of the ambitious climate policies agreed in the coalition deal with the Greens, which he was closely involved in drafting in 2021. “The climate emergency is a real and present threat to our society, but we need to recognise that the pursuit of net zero has to take people and business with us,” Swinney said. “When resources are limited, they must be used forensically to make the greatest impact on the challenge we face.” Holyrood’s delicate balance of power also brings the Scottish Liberal Democrats – Holyrood’s fifth largest party, with four MSPs – back into the mix as a counter-balance to the Greens. Swinney will spend the weekend working on a reshaped policy platform and a new cabinet, which is widely expected to include Forbes in a senior role, perhaps as deputy first minister, and junior ministerial posts for her allies. He said he had offered Forbes “a significant part” in his cabinet, adding: “She’s an intelligent, creative and thoughtful person who has much to contribute to our national life.” The pair had held private talks on Tuesday, which suggested they were likely to broker a deal. Swinney said he planned to govern from the centre-left and prioritise the economy, child poverty, the climate, the NHS, transport and housing. The current government strategy to hold down rental costs, championed by the Greens, is likely to be watered down to promote private-sector housebuilding. “My goals as first minister will come straight from that moderate centre-left tradition – the pursuit of economic growth and of social justice,” he said. “Economic growth, not for its own sake, but to support the services and society we all want to see.” The Tories and Scottish Labour claimed Swinney was a far weaker candidate than he appeared, given he had been intimately involved with all the SNP’s policy failures – as a finance secretary under Alex Salmond and Nicola Sturgeon, and as Sturgeon’s deputy first minister. Douglas Ross, the leader of the Scottish Conservatives, said at first minister’s questions: “They think John Swinney is a safe pair of hands – but he dropped the ball dozens of times.” Anas Sarwar, the Scottish Labour leader, said: “When our country is crying out for change, what is the SNP’s answer? An internal stitch-up and more of the same.”